The contractor shall attempt to: study conditions for stimulation of isolated amplifier or precursor T cells so as to allow amplification of cytotoxic responses to syngenic cells which bear tumor sepcific antigens but no allogeneic IA antigens. Attempts shall be made to: Elucidate mechanisms involved in suppression of cutotoxic responses to tumor cells and; to develop a system for generating strong cytotoxic responses to syngenic tumor cells.